The improvements of the invention are adapted especially for use in stator assemblies for torque converter transmissions in an automotive vehicle drive-line. The invention may be used also in other applications, however, such as torque transfer drives and chain drives that require an overrunning coupling in a torque flow path.
Torque converter transmissions include a stator assembly having a stator hub secured to a stationary sleeve shaft and stator blades situated between a toroidal flow exit section of a hydrokinetic turbine and the toroidal flow entrance section of a hydrokinetic impeller. The blades of the stator change the direction of the tangential component of the toroidal flow velocity vector at the turbine exit section prior to entry of the toroidal flow to the impeller entrance section. This permits multiplication of torque as the hydrokinetic converter delivers engine power to a power input element of multiple ratio gearing in the transmission mechanism.
It is known practice in the automotive transmission art to design the stator assembly of a hydrokinetic torque converter transmission with a stator hub that is adapted to receive an overrunning coupling having an outer race and an inner race, the inner race being splined to a stationary sleeve shaft and the outer race being carried by the bladed section of the stator assembly. The outer race typically would be cammed to provide a plurality of cam surfaces that are engageable by overrunning coupling rollers. The overrunning coupling permits reaction torque delivery from the stator blades to the stationary sleeve shaft when the torque converter is in a torque multiplication mode. The rollers and the cam surfaces with which they interact will permit freewheeling motion of the bladed section of the converter when the torque converter is in a coupling mode.
The outer race of a conventional overrunning stator coupling is keyed or splined in a central opening in the stator hub. It is held in place by snap rings located in snap ring grooves machined in the stator hub.
Prior art stator constructions for hydrokinetic torque converters typically are made of aluminum alloy or a phenolic resin. They are formed in a die cast operation or an injection molding operation wherein the inner and outer shrouds of the stator blades and one end wall of a stator hub comprise a unitary casting or molding. Such constructions require the formation of a keyway or internal spline tooth space in the stator hub. The outer race of an overrunning coupling, which is located in the stator hub, has a cooperating key or spline tooth arrangement to permit the overrunning coupling outer race to be locked in the stator hub. In the alternative, the keyway or spline tooth spaces may be formed in the coupling outer race and a cooperating key or spline tooth arrangement may be formed in the hub. The overrunning coupling assemblies in such arrangements are held in place by a spacer that is secured within the converter hub and held in place by a snap ring or the like.
Such prior art designs typically lack economy of space because they have an undesirable axial length. They also require a relatively large number of parts and machining operations during manufacture. Further, they require retainer rings or the like with retainer grooves that require finished machining operations on the stator hub.
While embodiments of the invention will be illustrated and described it is anticipated that various modifications and alternative designs may be made without departing from the scope of the invention.